The present invention belongs to the field of ink jet recording in which ink is ejected as ink droplets, and relates more specifically to an ink jet head for ejecting ink droplets by causing electrostatic force to act on the ink, and an ink jet recording device and an ink jet plate making apparatus using the ink jet head.
In an electrostatic ink jet recording system, ink having an electric charge is used and ink ejection is controlled by utilizing electrostatic force through application of a predetermined voltage (drive voltage) to ejection electrodes (drive electrodes) of an ink jet head corresponding to image data to record an image corresponding to the image data on a recording medium. For example, the ink jet recording device disclosed in JP 10-138493 A is known as the electrostatic ink jet recording device.
In JP 10-138493 A, there is disclosed the ink jet recording device as an example of the electrostatic ink jet recording device in which ink guides are provided to extend through through holes that function as nozzles from which ink is ejected and ejection electrodes are disposed on the peripheries of the through holes. The ink jet recording device disclosed in JP 10-138493 A generates electric fields around the through holes through application of voltages to the ejection electrodes corresponding to recording data, causing the force from the electric fields act on the meniscuses of the ink formed at the through holes, and ejects the ink droplets from the through holes to a recording medium.
Such the electrostatic ink jet recording system is capable of forming fine droplets and drawing images with high resolution. Specially, the electrostatic ink jet recording system which uses the ink prepared by dispersing charged colorant particles in an insulative solvent hardly causes bleeding of ink dots on a recording medium, so that it can be used for image recording for various recording media.
Such the electrostatic ink jet recording device can be produced at low cost by making the head itself small.
However, in the ink jet head disclosed in JP 10-138493 A, when the ejection portions (channels) are disposed at high density for making the head small (that is, when the ejection portions are disposed in a highly integrated manner), the electric field generated at an ejection portion influences the electric field generated at an adjacent ejection portion, that is, electric field interference occurs between adjacent ejection portions, which may cause a problem in that ink ejection at the ejection portions becomes unstable. Unstable ink ejection would cause an error in ink ejection, displacement of positions to which ink is adhered and the like, thereby making it difficult to form images with high quality and high definition.
Further, when the ejection portions are disposed at high density, it is difficult to maintain the insulating properties between adjacent ejection portions.